Particleboard is made by forming a mat of particles mixed with an appropriate normally heat-activatable binder on a conveyor belt. This mat is prepressed between rollers and then normally subdivided into panels that are hot pressed into finished boards that are trimmed to size for the end user. Equipment for doing this is described in U.S. Pat. Nos. 4,468,188, 4,647,417, 4,645,632, and 4,681,523 as well as in the patents and references cited therein.
The mat-forming apparatus typically comprises a dispensing roller having a plurality of like axially spaced disks carried on a rotating horizontal shaft. A reinforced synthetic-resin conveyor belt has a horizontal upper stretch spaced below this drum and is continuously driven to move this upper stretch longitudinally downstream. Binder-coated particles are fed to the drum and pass through it to land on the conveyor belt and form a mat of uniform thickness that is subsequently processed as described above into a particleboard (which term is here intended to cover chipboard, fiberboard, and similar materials formed of particles that themselves do not extend the full width, thickness, or length of the finished product).
In order to preform the mat and prevent the particles from spilling outside the machine, walls are provided extending longitudinally along each side of the area of the conveyor belt on which the particles are dropped by the dispensing drum. These walls are formed of sheet metal plates. When the mat-forming space is long it is necessary to use a succession of lapped plates. As a result the edge of the mat thus formed is not very neat, in particular when long particles or fibers are being deposited, as the slight change in width where one plate ends and the next one starts can disrupt the fibers at the edge of the mat.
It is also standard to change the overall height of the distributing space, typically by raising or lowering the dispensing rolls, in order to achieve a different effect or to use a different type of particle. When such a height change is made it is therefore necessary to swap out the wall plates altogether with ones having the desired height, so that down time for such a change is substantially increased.